A Controllable Secondary Multikilowatt DC Current Source With Constant Maximum Power Factor in its Three-Phase Supply Line

Novel operation and control modes for series-resonant converters

“…Two important conclusions can be extracted from (6) and (7 (10) 2) when Es + V, < vcp(k) < 2Es: converter will operate in an asymmetrical mode (11) 3) when vcp(k) > 2E. : symmetrical converter operation is feasible.…”

“…To increase the reliability of s.r.-converters, usually [7] the occurrence of condition (10) is monitored in some way (reverse-bias detection) and used to interrupt converter operation in case of pending turnoff failure. In the following section it will be shown that these interruptions may frequently occur in normally operated multiphase s.r.-converters, due to the absence of condition (10).…”

“…In the following section it will be shown that these interruptions may frequently occur in normally operated multiphase s.r.-converters, due to the absence of condition (10). Moreover, it will be shown that a control method exists which guarantees the occurrence of condition (12) [5], [7], [8] in fact necessary to control the capacitor peak voltage independently from the average current and maintain it at a sufficiently high value. The problem stated above can be solved by taking advantage of the specific structure of multiphase s.r.-converters.…”

A DC to 3-Phase Series-Resonant Converter with Low Harmonic Distortion

“…Some successful experiments of ac-dc s.r.-converters were reported by Schwarz [7], [8]. Recently, a singlephase dc-ac converter has been presented [9].…”

“…The 30-dc (3-phase to dc) s.r.-converters described up to now [7], [8] do, however, extract currents from the power grid which are similar to the currents which are extracted by a 3-phase diode rectifier. These square-wave-like currents cause harmonics in the supply lines, while the power factor is theoretically limited to 0.955 [8].…”